This invention relates to a two-stage combustion system and method utilizing a fluidized bed reactor, and, more particularly, to a system and method in which a secondary combustion assembly is provided for secondary combustion of unreacted flue gases containing NOx.
The use of two stage combustion in a fluidized bed system is generally known. For example, Engstrom et al., U.S. Pat. No. 4,616,576, discloses a two stage combustion method in which two circulating fluidized bed systems with their associated cyclone separators are utilized in a series connection to provide an efficient method of combustion with reduced NOx emission. However, the use of a second fluidized bed results in a significant complication of the operational control, substantial systems redundancy and associated increase in system cost. Further, both the fluidized bed and the cyclone separator are subject to wear due to the abrasive action of the circulating particulate matter.